1. Field of the Invention
The present invention relates to an apparatus for controlling discrete data in a disk overwrite area or a power calibration area, and more particularly to an apparatus for controlling discrete data produced between two data clusters when reading a data burned into a Blu-Ray disc.
2. Description of Related Art
Since people are increasingly having higher requirements for optical storage products and technologies, optical discs have evolved from CDs and DVDs to Blu-Ray discs. Thereby the capacity of discs has increased from a CD's capacity of 650 MB and a DVD's capacity of 4.7 GB to the Blu-Ray disc's capacity of 22 GB. The laser wavelength has become shorter, the track pitch has become smaller, and the pit on the disc has become shorter. Because of these changes the level of difficulty for decoding data becomes relatively high.
Refer to FIG. 1 for a schematic view of discrete data produced between two data clusters when a Blu-Ray disc is burned and FIG. 2 for another schematic view of discrete data produced between two data clusters when a Blu-Ray disc is burned. After the previous data cluster (k−1) 10 is written and before the next data cluster (k) 14 is written, a run-out area 11 and a guard area 12 will have a run-in area 13, and these two data clusters 10, 14 can be written from different optical disk drives or written twice from the same optical disk drive. If the two data clusters 10, 14 are written from different optical disk drives, the properties of signals in the data area behind the run-in area 13 and in front of the next data cluster 14 will have discrete phenomenon, such as the magnitude of signals. Even if the two data clusters 10, 14 are written from the same optical disk drive, there will be a data overwrite area between the two data clusters, and thus the phase and frequency of the clock will be discrete. For example, a sync signal will produce several irregular sync signals such as a second sync signal 17 and a third sync signal 18 after going through a first sync signal 15 and a run-out area sync signal 16, and will then recover its normal sync signal such as a fourth sync signal 19 and a fifth sync signal 20.
The specifications of a Blu-Ray disc include a power calibration area (PCA) 21 designed in front of the foregoing run-in area 13. In the power calibration area 21, various patterns and laser powers are used for the write-in testing, and the properties of the signals are similar to or even worse than those of the foregoing overwrite area.
Therefore, the signals of a rewritable disc (RW disc) or a recordable disc (R disc) that allow data to be written in certain continuous sections will become poor in these areas or different from the normal adjacent front or rear signals in the areas, since the signals are written or tested repeatedly. As a result, it will be difficult to decode the data.
Referring to FIG. 3A for the block diagram of a prior art optical disk drive signal processing system, the signal processing system adopts a digital processing structure. A pick up head (PUH) 31 reads a radio frequency signal on an optical disc 30 and outputs the radio frequency signal to an amplifier 32, and then the amplifier 32 amplifies the radio frequency signal. After an analog to digital converter (ADC) 35 converts a radio frequency analog signal into a radio frequency digital signal and outputs the radio frequency digital signal to an equalizer 33, an auto gain control (AGC) 34 adjusts the amplifier 32 according to the digitized radio frequency signal to maintain the magnitude of the radio frequency signal, and the equalized signal goes through a slicer level controller 36 to remove the low and mid frequency portions of the data, so that the center can be aligned correctly, and a basic clock (PLCK) is obtained from a phase lock loop (PLL) 37, and an adaptive Viterbi decoder 38 and a demodulator 39 decode the required data for output.
Referring to FIG. 3B for the block diagram of a prior art optical disk drive signal processing system, the signal processing system adopts an analog processing method. The pick up head 31 reads a radio frequency signal from the optical disc 30 and outputs the radio frequency signal to the amplifier 32, and the amplifier 32 amplifies the radio frequency signal, and the auto gain amplifier 34 adjusts the amplifier 32 according to the digitized radio frequency signal to maintain the magnitude of the radio frequency signal and uses the equalizer 33 to compensate the radio frequency signal. The equalized signals go through the slicer level controller 36 and a comparator 40 to remove the mid and low frequency portions of the data, so that the center can be aligned correctly. The analog to digital converter 35 converts analog signals into digital signals, and the phase lock loop 37 takes out a basic clock and uses a demodulator 39 to decode the required data for output.
When the foregoing prior art optical disk drive signal processing system processes discrete data produced between two data clusters of the Blu-Ray disc, errors often occur when the signals are used for processing related circuits such as the phase lock loop, slicer level control circuit, auto gain amplifier, equalizer, and adaptive Viterbi decoder, because the properties of signals in front of and behind the run-in area are very different. As a result, it takes more time to recover the related parameters, if possible, when recovering to the normal area, or a poor value is converged or a lock is lost causing a higher error percentage in the signal, and even resulting in failures of decoding signals or reading data.